Appendix 12B Solid Strata Around the Omagh Thrust Fault

A5 Western Transport Corridor Volume 3 – Appendices

APPENDIX 12B SOLID STRATA AROUND THE OMAGH THRUST FAULT

Table 12B.1 Strata to the North of the Omagh Thrust Fault (OTF)

NW Limb of Sperrin Age SE Limb of Sperrins Mountain Spatial Context Mountains Ballyshannon Limestone Formation (BAL) - Limestone, Present as a small wedge - dark bluish grey, some silty southwest of Omagh mudstone, fossiliferous; rare chert Claragh Sandstone Formation (CLSG) Sandstone, very coarse North of the OTF. In the area to - grained, fine conglomerate, fawn the north and west of Mountjoy and grey, arkosic; thin limestone; down to Gillygooly

isean grey mudstone with micropores V Owenkillew Sandstone Group (OWSA) - Greenish grey and purplish red sandstone and North of the OTF Around the - siltstone with thin beds of algal Victoria Bridge area laminated limestone. Dark grey mudstones contain microspores Omagh Sandstone Group North of the OTF, around (OMSG) - Red sandstone with - Gortnagarn, Knockmoyle and calcrete nodules and pebbles of west of Gilygooly white quartz. Palaeozoic Carboniferous Tournaisian Mullaghcarn Formation (MCA) – Located immediately to the north - Schistose semipelite, psammite of the OTF, with the exception of and pelite the area around Omagh DCCF – Located in the north west of the engineering study Claudy Formation (DCCF) area, underlying Sion Mills and Glebe Psammite, quartz and Dart Formation (DART) feldspar rich, coarse DART – Located in the north east detritial grains of blue Volcaniclastic semipelite and of the engineering study area on quartz and pink and white schistose amphibolite the east of the Mourne River, feldspar; minor semipelite, down to Gortinagin, with the limestone and green beds exception of the Newtownstewart area Southern Highland Group Group Highland Southern Located to the north west and Dungiven Formation (DUNN) south east of the Pelite, semipelite, psammite, quartzite, basaltic lava flows and Newtownstewart Formation and volcaniclastic sediments underlying the settlement of Ardstraw

Newtownstewart Formation (DBNF) Located in the centre of the nappe, to the north west of Thickly bedded quartzose psammite with thin pelite interbeds Newtownstewart Precambrian Dalradian Argyll Group

Table 12B.2 Strata to the South of the Omagh Thrust Fault

South of the Omagh Thrust Description Spatial Context Age Fault Dolerite and Basalt (D) Olivine Basalt and Dolerite, South west of Seskinore. Only intermediate grain size intrusive present as a thin wedge.

and lava flow igneous strata, associated with the Antrim

Palaeogene Palaeogene Basalts.

Slievebane Group (SLI) Undivided – Volcaniclastic South of the OTF. Only conglomerate and sandstone, present as a small wedge thin mudstone Westphalian Ballinamallard Mudstone Mudstone and siltstone, greyish In the area of Seskinore and to Formation (BLM) red, rarely greyish green the west.

Greenan Sandstone Formation Medium to coarse grained North of Edenderry Only

Namurian (GNNS) sandstone with thin laminations present as a thin wedge of mudstone Carrickaness Sandstone Coarse-grained, pebbly lithic Present as two wedges to the Formation (CRSF) sandstone. South East, the larger spreading west to Aughnacloy. Meenymore Formation (MEF) Sandstone, brown; micritic Present as two small wedges

Carboniferous Carboniferous limestone; mudstone, grey with to the South of Augher. sparse marine fauna of corals, brachiopods and nautiloids. Dartry Limestone Formation Limestone, dark grey, bluish Occurs as several small (DARL) black chert, fine-grained, fine- wedges to the South of grained, fossiliferous; thin Augher. mudstone. Maydown Limestone Is a Limestone formation with Present to the North of Palaeozoic Formation (MYLF) abundant Asbian corals and Aughnacloy and to the west of branchiopods. Ballygawley covering a large area. Visean Bundoran Shale Formation Mudstone, dark grey, yellow Present as a wedge to the (BUNS) staining; with siltstone, South East of Aughnacloy. calcareous fossiliferous limestone. Thin basal multicoloured clay.

Clogher Valley Formation Fossiliferous mudstone, Occurs in the Clogher Valley (CVG) siltstone, sandstone and thin Present as many wedges to crinoidal limestone. the south along two fault lines. Ballyness Formation (BYC) Red and purplish red sandstone Occurs to the south of and conglomerate. Ballygawley Present as many wedges to the south along two fault lines. Raveagh Sandstone Formation Sandstone, very coarse grained, South east of Seskinore. Only (RSF) fine conglomerate, fawn and present as a thin wedge. grey, arkosic. Upper Upper Devonian

South of the Omagh Thrust Description Spatial Context Age Fault Gortfinbar Conglomerate Conglomerate, purplish brown, Limited presence to the south Formation (GOCF) clasts boulder and pebble sized, of the Shanmullagh Formation, volcaniclastic, rare vein quartz, along the Killadeas-Seskinore quartzite and greywacke; Fault. sandstone, coarse-grained. (subsidiary vesicular, flow banded lava) Shanmaghery Sandstone Sandstone, purplish brown, red North East of Section, South Formation (SMSF) and green stained, coarse- of Six Mile Cross. Only grained, calcareous, micaeous, present as a thin wedge.

Middle Middle fining upwards, with thin siltstone and mudstone intercalations; parallel, cross and ripple laminations and desiccation cracks. Basal conglomerate with pebbles of vein quartz, quartzite, biotite granite, tuff, jasper and mica schist. Shanmullagh Formation Brown coarse grained pebbly Covers a wide area to the (SHAN) sandstone, thin purplish grey north of the Tempo- fine-grained sandstone and Sixmilecross Fault. mudstone. Also consists of purplish grey sandstone and mudstone laminae with ripples. Lower Lower Sandstone also in channels (up to 2 m deep) & consists of sand siltstone, reddish brown mudstone.

Tyrone Volcanic Group (TVG) Intermediate Lavas and A small wedge south of the volcanistic tuffs, rhyolites, OTF to the south east of

banded chert, jasper and Omagh argillaceous sediment Ordovician